Bicyclic beta-lactam/paraben complexes

Abstract: The invention provides complexes of the formula: wherein X is chloro, hydrogen, vinyl, or -CH₃, Z is CH₂, S, or O; n is 0-5; Y is phenyl or 1,4-cyclohexadien-1-yl; R₁ and R₂ are hydrogen or hydroxy, with the proviso that R₁ and R₂ are not both hydrogen and R₃ is -COO⁻, -COO(C₁-C₄ alkyl),-NO₂ or wherein R₄ is C₁-C₄ alkyl.

Description: This invention relates to novel cephalosporin and carbacephalosporin/paraben complexes, and methods of use of such, particularly for isolation and purification of the β-lactam antibiotic. Cefaclor, cephalexin, cephradine and loracarbef have the structures as set out below: The four β-lactam compounds, in which the C-2' (*) asymmetric centers have the R absolute configuration, are commercially important oral antibiotics. Various references discuss isolation and/or purification processes for the β-lactam compounds, such as that found in European Patent Application 0,341,991 published November 15, 1989. In that EPO application is disclosed the use of anthraquinone-1,5-disulfonic acid to form a pharmaceuticallY acceptable salt with the particular cephalosporin or carbacephalosporin, which allows for recovery of the β-lactam from mother liquors after crystallization. As these antibiotics are expensive to make, new and improved procedures for such recovery are continually being sought in order to maximize overall yield. The commercially important antibiotics cephalexin, cefaclor, cephradine and loracarbef have been observed to form crystalline complexes with parabens and related compounds. Complexes of cephalosporins which can be used for isolation or purification, are disclosed in EP-A-0,003,329, EP-A-0,308,123 and US-A-5142042. The present invention is directed to complexes of the formula wherein X is chloro, hydrogen, vinyl or -CH 3 , Z is CH 2 or S; n is 0-5; Y is phenyl or 1,4-cyclohexadien-1-yl; R 1 and R 2 are hydrogen or hydroxy, with the proviso that R 1 and R 2 are not both hydrogen and R 3 is CO 2 H, -COO(C 1 -C 4 alkyl), -NO 2 or wherein R 4 is C 1 -C 4 alkyl. Further, the invention is directed to the preparation of the above complexes in order to recover antibiotic material. The terms "complex" and "cocrystal" are used to describe the single solid state phase resulting from the combination of the antibiotic and the paraben or related compound. The preparation and isolation of cephalexin, cefaclor, cephradine, or loracarbef paraben complexes are simple and straightforward. Aqueous and substantially aqueous solutions or suspensions of the β-lactam and paraben or related compound are mixed and the components are allowed to co-crystallize at a temperature in the range of 0 to 65°C. The preferred amount of paraben or related compound added is 1 to 3 equivalents per equivalent of β-lactam used. In each case, formation of cocrystals was demonstrated by its unique X-ray powder pattern which differs from the published X-ray powder patterns for cephalexin (L.P. Marelli, Analytical Profiles of Drug Substances,4, pp. 21-46 (1975)); cephradine (K. Florey, Analytical Profiles of Drug Substances, 5, pp. 21-59 (1976)); cefaclor (L.S. Lorenz, Analytical Profiles of Drug Substances, 9, pp. 107-123 (1980)); loracarbef monohydrate [Pasini, European Patent Application EP 0311366 A1, published April 12, 1989) and loracarbef dihydrate (Eckrich et al ., European Patent Application 0369686 A1, published May 23, 1990); methyl, ethyl, and propyl paraben, methyl 3-hydroxybenzoate and acetophenones. Neither cefadroxil, nor the arylglycine penicillins, amoxicillin and ampicillin, formed appreciable levels of either methyl or propyl paraben cocrystals in our laboratory. Crystalline complexes of the β-lactams with parabens and related compounds may be used in recovery, isolation, and/or purification processes of the β-lactam. The cocrystals can be used to precipitate the β-lactam from dilute solutions (for example mother liquors or reaction solutions). The cocrystals can be isolated by filtration. To recover the β-lactam, the cocrystals can be dissolved in an acidic organic solvent or an acidic aqueous organic solvent system. Suitable acids are known in the art and include, for example, hydrochloric, sulfuric and hydrobromic acids. Suitable solvents include ethanol, n-butanol, methyl isobutyl ketone, diethyl ether, diisopropyl ether, ethyl acetate, methylene chloride, tetrahydrofuran, dimethylformamide, dimethylsulfoxide, and aqueous mixtures thereof. The β-lactam is isolated from the resulting solution by raising the pH of the mixture to precipitate the β-lactam while the paraben or related compound remains in solution. Suitable bases are known in the art and include ammonium hydroxide, sodium hydroxide, and triethylamine. The isolation of the β-lactam may take place between 0-50°C. Alternatively, the cocrystals may be dissolved in a basic organic solvent or basic organic aqueous solvent system and the β-lactam precipitated by lowering the pH. In either case, the β-lactam is collected by filtration and may be used as is or converted to a more desirable crystal form. Experimentals General Methods Table 1, illustrates the X-ray powder diffraction patterns for the products of Examples 1-5, wherein "d" is the interplanar spacing and is measured in Angstroms and "I/I 0 " is the relative intensity. Example 1 Cephalexin:Methyl Paraben · H 2 O Methyl paraben (375 mg, 2.5 mmol) in 150 ml of water was added to cephalexin monohydrate (2.4 g, 6.6 mmol) to result in a suspension. After 5 days at 5°C, the crystals were collected by filtration and washed with water to give 1.06 g (2.0 mmol) of cocrystals. mp 168-169°C. Anal. - calcd for C 24 H 25 N 3 O 7 S . H 2 O: C, 55.70; H, 5.26; N, 8.12. Found: C, 55.65; H, 5.28; N, 8.13. HPLC assay (calcd), found: (67.1), 67.1% cephalexin, (29.4), 28.7% methyl paraben. KF (Calcd), found: (3.5), 4.0% water. Example 2 Cephradine:Methyl Paraben · H 2 0 Methyl paraben (250 mg, 1.6 mmol) in 100 ml of water was added to cephradine monohydrate (1.6 g, 4.4 mmol) to result in a suspension. After 3 days at 25°C, the crystals were collected by filtration and washed with water to yield 0.609 g (1.2 mmol) of cocrystals with 1 mol of water of crystallization. mp 167-168°C. Anal.-calcd for C 24 H 27 N 3 O 7 S . H 2 O: C, 55.48; H, 5.63; N, 8.09. Found: C, 55.58; H, 5.57; N, 8.08. HPLC assay (calcd), found: (67.2),67.7% cephradine, (29.3), 28.9% methyl paraben. KF (calcd), found: (3.5), 3.7% water. Example 3 Cefaclor:Methyl Paraben · 3H 2 O Methyl paraben (250 mg, 1.6 mmol) in 100 ml of water was added to cefaclor monohydrate (1.3 g, 3.4 mmol) to give a suspension. After 5 days at 5°C, the crystals were collected by filtration and washed with water to give cocrystals with 3 mol of water of crystallization, mp 142°C dec. Anal.-calcd for C 23 H 22 ClN 3 O 7 S . 3H 2 O: C, 48.13; H, 4.92; N, 7.32. Found: C, 48.01; H, 4.92; N, 6.99. HPLC assay (calcd), found: (64.1), 65.0% cefaclor, (26.5), 25.4% methyl paraben. KF (Calcd), found: (9.4), 9.9% water. Example 4 Loracarbef:Methyl Paraben Methyl paraben (460 mg, 3.0 mmol) in 230 ml of water was added to loracarbef monohydrate (3.0 g, 8.2 mmol) to give a suspension. After 25 days at 25°C the crystals were isolated by filtration and washed with water to give 0.72 g (1.4 mmol) of cocrystals. mp 191°C dec. Anal.calcd for C 24 H 24 ClN 3 O 7 : C, 57.44; H, 4.82; N, 8.37. Found: C, 57.16; H, 4.92; N, 8.59. HPLC assay (Calcd), found: (69.7), 70.6% loracarbef, (30.3), 30.0% methyl paraben. Example 5 Loracarbef:Propyl Paraben Propyl paraben (500 mg, 2.8 mmol) in 500 ml of water was added to loracarbef monohydrate (5.5 g, 14.9 mmol) to give a suspension. After 20 days at 5°C, the crystals were recovered by filtration and washed with water to yield 1.31 g (2.5 mmol) of cocrystals. mp 178°C dec. Anal. Calcd. for C 26 H 28 ClN 3 0 7 : C, 58.92; H, 5.32; N, 7.93. Found: C, 58.69; H,5.31; N, 7.90. HPLC assay (calcd), found: (66.0), 64.31% loracarbef, (34.0), 33.3% propyl paraben. Example 6 Loracarbef:Ethyl Paraben The pH of aqueous loracarbef monohydrate mother liquor (1000 ml, having 9.23 mg/ml of loracarbef monohydrate) was adjusted to 3.6 with HCl. Ethyl p-hydroxybenzoate (ethyl paraben) (4.52g) in ethanol (36 ml) was added dropwise over 15 minutes. After approximately 5 minutes, precipitation occurred, resulting in white crystals. The mixture was stirred overnight (15 hrs) at room temperature, filtered, washed with H 2 O, and dried under vacuum at 40°C. The yield was 11.72 g having a potency of 73.5% as loracarbef, and the theoretical yield was 8.78 g as loracarbef, resulting in a percent yield of 98.2%. The loracarbef:ethyl paraben exhibited the following X-ray powder diffraction pattern: d (I/I 0 ) 12.03778 100.0 10.51978 2.7 8.87879 28.6 7.24748 4.0 6.04328 1.6 5.77434 39.3 5.27012 2.9 4.95456 3.6 4.80014 0.6 4.60833 2.7 4.50920 2.6 4.03255 38.1 3.57845 38.9 3.54171 4.3 3.35279 22.4 3.20988 1.4 3.16843 0.7 3.02715 4.6 2.89099 3 9 2.83791 0.5 2.80444 1.0 2.76760 1.9 2.69465 1.5 2.62614 1.6 Example 7 Loracarbef:Methyl 3-Hydroxybenzoate . 5H 2 O Methyl 3-hydroxybenzoate (496 mg, 3.3 mmol) in 3 ml of 95% EtOH was added to loracarbef monohydrate (1.2 g, 3.3 mmol) in 200 ml of water. After 19 days at 25°C, the crystals were collected by filtration and washed with water to yield 576 mg (0.97 mmol) of cocrystals. Anal, calcd for C 24 H 24 ClN 3 O 7 . 5H 2 O: C, 48.69; H, 5.79; N, 7.10. Found: C, 48.84; H. 5.56; N, 7.23. Example 8 Loracarbef:Methyl Paraben Loracarbef ethanolate (2.55 g, 74.7% as loracarbef) was suspended in 100 ml of H 2 O. NaOH (1.0 N, 1.08 ml) was added, and the pH was raised to 8.9. The mixture was stirred until the loracarbef was almost dissolved. Methyl p-hydroxybenzoate (methyl paraben) (0.83 g) in 7 ml of ethanol was added, and the pH dropped to 8.1 within several minutes. The mixture became turbid as the solid began to precipitate. The mixture was stirred at room temperature for 2 hours, filtered, washed with H 2 O and dried overnight under vacuum at 40°C. The yield was 1.92 g, the theoretical yield as cocrystal was 2.83 g, with a percent yield of 67.8%. Example 9 Loracarbef:Butyl Paraben Loracarbef ethanolate (2.55 g, 74.6% as loracarbef) was added to 100 ml of H 2 O. The pH was adjusted to 8.4 with NaOH (1.0M, 1.08 ml). After stirring for 30 minutes at room temperature, the solution was almost clear. Butyl p-hydroxybenzoate (butyl paraben) (1.06g) in 7 ml ethyl alcohol was added to the mixture. The mixture was stirred for several hours at room temperature, filtered, washed with H 2 O and dried under vacuum of 40°C. The titled product was white. The actual yield was 1.78 g, the theoretical yield was 3.06 g as cocrystal with a percent yield of 58.2%. Example 10 Loracarbef:Ethyl paraben Loracarbef ethanolate (2.55 g, 74.7% as loracarbef) was suspended in 100 ml H 2 O. NaOH in a molar excess was added, the pH rose to 8.4, and a clear mixture was obtained. Ethyl p-hydroxybenzoate (0.90 g, 5.44 mm) in 7 ml ethyl alcohol was added to the mixture, and within several minutes a thick precipitate formed. The pH was 9.95. The mixture was stirred several hours at room temperature, filtered, washed with H 2 O and dried under vacuum at 40°C. The actual yield was 2.08 g, the theoretical yield as cocrystal was 2.90 g, and the % yield was 71.7%. Example 11 Loracarbef:Propyl Paraben Loracarbef ethanolate (2.55 g, 74.7% as loracarbef) was suspended in 100 ml H 2 O. NaOH (1 N, 1.08 ml) was added and the pH was 7.2. A further amount of 1N NaOH was added to raise the pH to 8.2. Propyl p-hydroxybenzoate (0.90 g, 5.44 mm) in 7 ml ethyl alcohol was added to the mixture, and immediately a white solid precipitated. The mixture was stirred at room temperature for several hours. The mixture was filtered, washed with H 2 O and dried under vacuum at 40°C. The pH of the filtrate was lowered to 4.9, but no additional precipitation was observed. The actual yield was 0.90 g, the theoretical yield as cocrystal was 2.98 g, and the % yield was 30.2%. Example 12 Loracarbef:Ethyl Paraben An acylation reaction was run according to US patents 4,316,958, 4,332,896 and 4,335,211. The acylation reaction mixture was extracted with methylene chloride and the aqueous phase filtered. Ethyl paraben (3.82 g) was dissolved in 3 ml of ethyl alcohol and added to the aqueous solution containing 4.23 g of loracarbef as the monohydrate. The solution began to crystallize and the pH was lowered to 4.3 with hydrochloric acid. The mixture was stirred for several hours at room temperature. The mixture was cooled overnight in a refrigerator, filtered, washed with water, and dried under vacuum at 45°C. The actual yield was 8.37 g, 39% potency as loracarbef, the theoretical yield was 3.99 g as loracarbef and the % yield was 81.2%. Example 13 Loracarbef:Ethyl Paraben Ethyl paraben (3.50 g) was dissolved in 30 ml of ethyl alcohol and added to aqueous loracarbef monohydrate (3.88 g, 10.55 mm). The pH was lowered to 3.5 with hydrochloric acid and the suspension was stirred for several hours at room temperature. The suspension was cooled to 5°C for several hours, filtered, and dried under vacuum at 55°C. The actual yield was 6.35 g, 55.3%, potency as loracarbef, the theoretical yield was 3.69 g, and the % yield was 95.1%. Example 14 Loracarbef DMF Disolvate To a mixture of loracarbef: ethyl paraben (1.34 g, 65.5% potency as loracarbef) in 18 ml of DMF and 1.8 ml of H 2 O was added concentrated hydrochloric acid sufficient to obtain a clear solution. The pH of the solution was slowly raised to 6.9 with triethylamine, and the crystallization of the titled product occurred quickly. The mixture was stirred for 1 hour at room temperature, filtered, washed with a solution of 10:1/DMF:H 2 O, and dried under a vacuum at 40°C. HPLC analysis indicated that no ethyl paraben was present. The actual yield was 1.01 g, 73.9% potency as loracarbef, the theoretical yield was 0.87 g as loracarbef, and the percent yield was 85.3%. Example 15 Loracarbef DMF Disolvate To loracarbef:ethyl paraben (15.0 g, 49.1% potency as loracarbef), predisolved in 150 ml DMF and 15 ml H 2 O was added concentrated hydrochloric acid (2.53 ml) dropwise. The solution was heated to 45°C and the pH was raised from 1.84 to 4.0 over 45 minutes using triethylamine. After crystallization began, triethylamine was slowly added until a pH of 6.7 was obtained. The mixture was stirred for 1 hour at 45°C, filtered, washed with DMF and ethanol and dried under vacuum at 40°C. HPLC analysis indicated that no ethyl paraben was present. The actual yield was 10.07 g, 72% as loracarbef activity, the theoretical yield was 7.37 g of loracarbef activity, and the percent yield was 98.4% yield. Example 16 Loracarbef Loracarbef:ethyl paraben (3.0 g, 49.1% as loracarbef) was suspended in 30 ml of 1:1 acetonitrile:H 2 O. The pH of the mixture was lowered to 1.9 with concentrated hydrochloric acid at which time a clear solution was obtained. The pH of the mixture was raised to 4.9 using triethylamine and a white precipitate formed quickly. The mixture was stirred for 1 hour, at room temperature, filtered, washed with 1:1/ acetonitrile:H 2 O, and dried under vacuum at 45°C. The actual yield was 1.36 g, 98.1% potency as loracarbef, the theoretical yield was 1.47 g, and the percent yield was 90.3%. Example 17 Loracarbef Ethanolate Loracarbef:ethyl paraben (11.26 g, 72.9% as loracarbef) was suspended in 90 ml of ethyl alcohol and 9 ml of H 2 O. Hydrochloric acid (3.5 ml) was added to obtain a clear solution, and the pH was approximately 0.80. To the mixture was added 5.0 ml of triethylamine in 30 ml of ethanol. The mixture was stirred for two hours, filtered, washed with ethanol, and dried under vacuum at 40°C. The actual yield was 8.22 g, 94.8% as loracarbef, the theoretical yield was 8.21 g, and the percent yield was 95.0%. Example 18 Loracarbef Monohydrate Loracarbef:ethyl paraben (30.0 g, 72.7% as loracarbef) was suspended in 240 ml of ethyl alcohol and 24 ml of H 2 O. To this mixture was added 9.0 ml of concentrated hydrochloric acid to obtain a clear solution. To the mixture, 15 ml of triethylamine and 84 ml of ethyl alcohol was added. The mixture was stirred for 1 hour at room temperature, filtered, and washed with ethanol, and dried under vacuum at 40°C to result in the loracarbef ethanolate. The actual yield of the loracarbef ethanolate was 22.59 g, 86.2% potency as loracarbef, the theoretical yield was 21.81 g of loracarbef activity, and the percent yield was 89.3%. Loracarbef ethanolate (5.0 g, 86.2%, potency as loracarbef), from above was suspended in 70 ml of H 2 O, and the slurry was heated to 50°C. The slurry became very thick which indicated conversion to the monohydrate. The slurry was stirred at 50°C for 1 hour, filtered, washed with H 2 O and dried under vacuum at 40°C. The actual yield of loracarbef monohydrate was 3.06 g, 102.8% potency as loracarbef monohydrate, the theoretical yield was 4.53 g, and the percent yield was 69.3%. Example 19 Cefaclor:4-Hydroxyacetophenone A solution of 265 mg (1.94 mmol) of 4-hydroxyacetophenone in 1 ml of ethanol was added to 750 mg (1.94 mmol)) of cefaclor monohydrate predissolved in 81 ml of water. The turbid solution was covered and allowed to stand at room temperature overnight, after which time very large, pale yellow crystals were recovered by filtration. mp 198-203°C (dec). %CHN calcd for C 23 H 22 C1N 3 O 6 S: C,54.81; H, 4.36; N, 8.34. Found C, 54.95; H, 4.51: N, 8.63. The cefaclor:4-hydroxyacetophenone exhibited the following X-ray powder diffraction pattern:

Claims: A complex of the formula wherein X is chloro, hydrogen, vinyl, or -CH 3 , Z is CH 2 or S; n is 0 to 5; Y is phenyl or 1,4-cyclohexadien-1-yl; R 1 and R 2 are hydrogen or hydroxy, with the proviso that R 1 and R 2 are not both hydrogen and R 3 is -CO 2 H, -COO(C 1 -C 4 alkyl), -NO 2 or wherein R 4 is C 1 -C 4 alkyl. A complex according to Claim 1 wherein said complex is cephradine:methyl paraben·H 2 O, cefaclor:methyl paraben·3H 2 O, cefaclor:ethyl paraben, 2 cefaclor:4-hydroxybenzoic acid·4H 2 O, cefaclor:3-hydroxybenzoic acid methyl ester·(1 or 5) H 2 O, cefaclor:4-hydroxyacetophenone, cefaclor:3-hydroxyacetophenone, cephalexin:methyl paraben · H 2 O, cephalexin:ethyl paraben·2H 2 O, cephalexin:3-hydroxybenzoic acid methyl ester·(0, 1, or 5)H 2 O, cephalexin:4-nitrophenol, cephalexin:3-hydroxyacetophenone, loracarbef: methyl paraben, loracarbef:ethyl parben, loracarbef:propyl paraben, loracarbef:3-hydroxybenzoic acid methyl ester·(1 or 5)H 2 O, loracarbef:4-hydroxyacetophenone, or loracarbef:3-hydroxyacetophenone. A process for preparing a compound of the formula which comprises the step of dissolving a complex as defined in Claim 1, in an acidic organic solvent or an acidic aqueous organic solvent mixture and thereafter adding a sufficient amount of base to precipitate the compound of formula (VI). A process according to claim 3 wherein said complex is cephradine:methyl paraben·H 2 O, cefaclor:methyl paraben·3H 2 O, cefaclor:ethyl paraben, 2 cefaclor:4-hydroxybenzoic acid·4H 2 O, cefaclor:3-hydroxybenzoic acid methyl ester·(1 or 5) H 2 O, cefaclor:4-hydroxyacetophenone, cefaclor:3-hydroxyacetophenone, cephalexin:methyl paraben · H 2 O, cephalexin:ethyl paraben·2H 2 O, cephalexin:3-hydroxybenzoic acid methyl ester·(0, 1, or 5)H 2 O, cephalexin:4-nitrophenol, cephalexin:3-hydroxyacetophenone, loracarbef: methyl paraben, loracarbef:ethyl parben, loracarbef:propyl paraben, loracarbef:3-hydroxybenzoic acid methyl ester·(1 or 5)H 2 O, loracarbef:4-hydroxyacetophenone, or loracarbef:3-hydroxyacetophenone. A process for preparing a compound of the formula which comprises the step of dissolving a complex as defined in Claim 1, in a basic organic solvent system or a basic aqueous organic solvent mixture and thereafter adding a sufficient amount of acid to precipitate the compound of formula (VI). A process according to claim 5 wherein said complex is cephradine:methyl paraben·H 2 O, cefaclor:methyl paraben·3H 2 O, cefaclor:ethyl paraben, 2 cefaclor:4-hydroxybenzoic acid·4H 2 O, cefaclor:3-hydroxybenzoic acid methyl ester·(1 or 5) H 2 O, cefaclor:4-hydroxyacetophenone, cefaclor:3-hydroxyacetophenone, cephalexin:methyl paraben · H 2 O, cephalexin:ethyl paraben·2H 2 O, cephalexin:3-hydroxybenzoic acid methyl ester·(0, 1, or 5)H 2 O, cephalexin:4-nitrophenol, cephalexin:3-hydroxyacetophenone, loracarbef: methyl paraben, loracarbef:ethyl parben, loracarbef:propyl paraben, loracarbef:3-hydroxybenzoic acid methyl ester·(1 or 5)H 2 O, loracarbef:4-hydroxyacetophenone, or loracarbef:3-hydroxyacetophenone.

Inventors: AMOS JANE GOEDDE, INDELICATO JOSEPH MICHAEL, PASINI CAROL ELAINE, REUTZEL SUSAN MARIE, AMOS, JANE GOEDDE, INDELICATO, JOSEPH MICHAEL, PASINI, CAROL ELAINE, REUTZEL, SUSAN MARIE
Applicants: LILLY CO ELI, ELI LILLY AND COMPANY
Application year: 1994
Main classification: C07D463
IPC codes: C07D501, C07D471, C07D505, C07D463, A61K31